Dummy joint cutter for concrete pavements



y 1933. w. T. M CLAIN DUMMY JOINT CUTTER FOR CONCRETE PAVEMENTS Filed April 23, 1930 m W W m A TTO/Q/VE).

Patented July 4, 1933 rear FlQE

WILLIAIWI THOMAS IvICGLAII'I, OF L08 ANGIE-LES, CALIFORNIA DUMMY JOINT CUTTER FOR CONCRETE PAVEMENTS Application filed April 23, 1930. Serial No. 446,570.

The present invention relates'to road con struction and particularly to an apparatus for cutting joints in concrete surfaces to allow for the change in volume resulting from 3 a change in temperature and that resulting from the natural shrinkage of the concrete material in the construction of roads. These changes in volume are responsible for the well known cracks that appear in road surfaces and constitute the chief annoyance of the road builder.

In building a road a subbase or foundation is provided and concrete in semiliquid form is poured thereon which forms a top coat or wearing surface. The top coat or wearing surface is divided up into sections by grooves extending generally acrosscthe entire wearing surface and serving to limit the expansive or contractive effects to each individual section. These grooves make planes of weakness; and a road laid without such grooves will in the course of a few days exhibit irregular cracks running lengthwise and. across the road. The remedy consists 5 in cutting the whole length into separate blocks or sections separated by a space sufficiently wide to allow each block or section to freely expand without coming into contact with its neighbor. This has been heretofore accomplished by means of wooden or steel parting strips across the forms at definite intervals.

In the present invention, I dispense with the parting strips and also with the use of the small hand jointer to provide grooves.

Thefprincipal object of my invention is to provide a novel apparatus for cutting dummy joints or grooves in concrete road surfaces, which involves the use of an improved dummy joint cutter in connection with a double straight edge lay off and guiding frame.

Heretofore, operations of this character have necessitated the use of bars embedded 45 in the concrete adapted to be removed to form the dummy oint groove which necessarily required the use of much material, time, and labor in connection with the placement of the bars on the road foundation and their subsequent removal to form the dummy joints or grooves.

Tt is another object of my invention to proylde an apparatus for forming dummy joints in concrete surfaces, which dispenses with the use of the heretofore mentioned section defining bars to produce dummy joints or grooves.

The present apparatus contemplates the use of a lay oif and supporting frame for the dummy joint cutter of my invention.

Another object of my invention is to pro: vide an apparatus consisting of a frame and a tool adapted for association therewith to form an accurate dummy joint or groove in concrete surfaces.

A further object of my invention is to provide an improved apparatus consisting of a tool and supporting frame which may be used in association to form dummy joints in concrete and which is of portable character, so that the same may be continuously usedfor the purposes described.

Another object of the invention is to provide dummy joint cutter which may be pulled along its supporting frame in a fnanner to form a relatively long and accuratelv defined cut in a concrete surface and whereiii the cutting element is adapted for replacement by other cutters to provide for cuts of different depth or for repairs.

A still further object is to provide a dummy joint cutter of compact assembly involving relatively few parts and which is self-lubrieating.

The invention is capable of receiving a variety of mechanical expressions, one of which is shown on the accompanying drawing, but it is to be expressly understood that the drawing is for the purpose of illustration only and is not to be construed as a. definition of the limits of the invention, reference being had to the appended claims for that purpose.

In said drawing Fig. 1 is a fragmental perspective view of my novel double straight edge frame and dummy oint cutting tool in position to cut a dummy joint r roove ina concrete surface.

Fig. 2 is an elevational view of my improved dummy joint cutting tool with portions in cross section and illustrating the construction and assembly of the operative parts.

Fig. 3 is an end elevation looking in the direction of the arrow in Fig. 2.

5 In concrete road construction it is necessary to provide for the contraction and expansion of the surface area of the road structure due to climatic and other conditions, and with this purpose in view, I have provided a novel means for accurately defining an area to be cut so that it may be divided off into sections which, when subjected to climatic conditions, will localize any detrimental effects caused by expansion or contraction of the concrete material and wherein any bulging of the material will limit the extent of the breakage or cracks to the area defined by the grooves, namely, the sections.

In Fig. 1, I have illustrated a frame used in conjunction with my improved dummy joint or groove cutter 11 illustrated more particularly in Figs. 2 and 3. This frame constitutes a very important part of my invention and comprises two flat horizontal bars 12 and 13 held in spaced relation at opposite ends by metal straps 14. Straight edges 15 and 16 formed of metal strips are secured to the confronting edges of the horizontal bars 12 and 13 and define a tool operating and guide space 17 between bars 12 and 13. Handle braces 18 are secured to bars 12 and 13 by bolts 19 which pass through the opposite ends thereof and the metal straps 14 and form the means for transporting the frame from place to lace as required.

esultant of the frame construction as above described, bearing surfaces 20 and 21 are provided on the upper part of the horizontal bars12 and 13; and the confronting surfaces of the metal straight edge strips 15 and 16 form the walls of the tool guide space 17.

The tool 11 used in conjunction with the frame 10 comprises an operating handle 22 formed preferably of galvanized pipe, and the lower end of said pipe is interiorly threaded at 23 for the reception of the threaded shank 24 of a clevis 25. The lower ends of the clevis arms 26 and 27 are provided with openings for the reception of an axle 28 which carries the grooving assembly of my invention, which will now be described.

Mounted preferably for rotation on the axle 28 is the grooving assembly comprising end rollers 29 and 30 and an intermediate roller 31 formed of two sections 32 and 33. Mounted on the axle 28 and clamped between the roller sections 32 and 33 by bolts 34 is the groove cutter disc 35 of my invention. In this manner the cutter disc 35 is solidly clamped and rotates with the roller sections 32 and 33. The peripheral portion of the disc 35 is formed with cutting teeth 36, and

I that portion of the cutter disc 35 projecting o5 outwardly from the peripheral surfaces of the roller sections 32 and 33 determines the depth of the groove to be cut in a concrete surface. The teeth 36 of the cutting disc 35 are of cross-cut conformation so that the same may be reversed in order to adapt the 7 cutting disc for double use. lVashers 37 and 38 are disposed on the axle 28 between the clevis arms 26 and 27 and the outer ends of rollers 29 and 30 to take up friction, and bearing caps 39 and 40 are screwed onto the ends of the axle 28 to hold the same in fixed position in the clevis arms 26 and 27. Lock nuts 41 and 42 are threaded on the ends of the axle and serve to lock the caps 39 and 40 against revolution thereon. A handle grip bar 42 for operating the groove cutter may be welded or otherwise secured to the handle 22.

The axle 28 is provided with a longitudinal groove 43 adapted for the reception of a lubricant which is fed through ports 44 to the inner bearing surfaces 45 of the roller sections 32 and 33. The rollers 29 and 30 are provided with lubricating chambers 46 adapted for lubricant which contacts with the outer side bearing surfaces of the roller sections 32 and 33 in a manner to lubricate the same.

After the concrete has been poured and properly laid off and set for approximately three and one-half hours, the top is marked off in sections by means of a chalk line and theframe 10 is lifted by the handles 18 so as to position the chalk line in the center of the space 17 between the straight edges 15 and 16 of the frame. Boards or planks may be extended across the concrete surface to support the operator of the tool 11.

The tool 11 is deposited on the outer end of frame 10 with the side rollers 29 and 30 rest- 5:105

.ing on the flat upper surfaces 20 and 21 thereof. The cutter disc 35 penetrates the concrete a predetermined distance which is determined by the depth of the groove desired to form the joints. When the cutting disc has penetrated the concrete resultant of the weight of the tool or pressure applied thereon, the sections 32 and 33 of the intermediate roller 31 contact with the surface of the concrete at each side of the cut and serve 0 equalize the pressure on the concrete at this point so as to hold the surface firmly in position during the grooving operation.

The tool 11 is pulled along the frame space 17 by the handle 22, and the cutting disc 35 I rotates and cuts a groove along the chalked line as above described. If the road surface is to be of a thickness of six inches, the groove may preferably be cut entirely through the surface, thoughin certain cases a groove of 1125 the thickness of approximately one and onehalf inches may be cut.

The frame 10 may be lifted by the end handles 18 and transported for cooperative use with the tool to outline the cement road sections with grooves or joints, which function to localize the adverse effect of temperature changes in the individual sections.

The grooving discs are interchangeable for use where different depths of grooves are required, the depth of the grooves being directly contingent upon the diametrical proportions of the discs.

After the grooves have been out they may be filled with tar poured thereinto in the usual manner.

I claim as my invention:

1. In an apparatus for cutting grooves in a road surface, the combination of: a frame comprising a pair of horizontal bars adapted for contact with said surface in spaced relation to a selected line; a cutting member associated with said frame; rollers on said cutting member adapted for movement on said bars for supporting said cutting member; and guide rollers on said cutting member operable in the space between said bars, said guide rollers contacting with said surface to equalize the pressure on said surface during the grooving operation.

2. In an apparatus for cutting grooves in a concrete surface, the combination of: a frame comprising a pair of bars adapted for contact with said surface in spaced relation to a selected line; and a grooving member oper able along said frame and including outer and inner rollers and a grooving disc disposed therebetween, said outer rollers adapted for movement along said bars for support ing said grooving member on said frame, and said inner rollers being operable in said space so as to exert pressure on said surface during the operation of said grooving disc.

3. In an apparatus for cutting grooves in a concrete surface, the combination of: a frame comprising a pair of longitudinally extending bars disposed in spaced relation to a line to be grooved; and a manually operable grooving member including, a pair of supporting rollers operable along said bars, a cutting disc, and a pair of surface contacting rollers operable through said frame space in a manner to equalize the pressure exerted on said surface during the operation of said cutting disc.

In testimony whereof, I have hereunto set my hand at Los Angeles, California, this 15th day of April, 1930.

WVILLIAM THOMAS MoCLAIN. 

